net: phy: micrel: set soft_reset callback to genphy_soft_reset for KSZ8061

Following a similar reinstate for the KSZ8081 and KSZ9031.

Older kernels would use the genphy_soft_reset if the PHY did not implement
a .soft_reset.

The KSZ8061 errata described here:
https://ww1.microchip.com/downloads/en/DeviceDoc/KSZ8061-Errata-DS80000688B.pdf
and worked around with 232ba3a5 ("net: phy: Micrel KSZ8061: link failure after cable connect")
is back again without this soft reset.

Fixes: 6e2d85ec

 ("net: phy: Stop with excessive soft reset")
Tested-by: Karim Ben Houcine <karim.benhoucine@landisgyr.com>
Signed-off-by: Mathieu Othacehe <othacehe@gnu.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>